/****************************************************************************
 * Copyright (c) [2019] [core.zhang@outlook.com]                            *
 * [Software Name] is licensed under Mulan PSL v2.                          *
 * You can use this software according to the terms and conditions of       *
 * the Mulan PSL v2.                                                        *
 * You may obtain a copy of Mulan PSL v2 at:                                *
 *          http://license.coscl.org.cn/MulanPSL2                           *
 * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF     *
 * ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO        *
 * NON-INFRINGEMENT, MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.       *
 * See the Mulan PSL v2 for more details.                                   *
 *                                                                          *
 ***************************************************************************/
#include "./lz_utils.h"
#include <string.h>

#define BYTE_ALGINED_REQUIRED
uint16_t char_hl_short(uint8_t chHigh, uint8_t chLow)
{
    return (((uint16_t)0xFFFF & chHigh) << 8) | chLow;
}

uint16_t short_xch_hl(uint16_t hwValue)
{
    return ((hwValue & (uint16_t)0x00FF) << 8) | ((hwValue & (uint16_t)0xFF00) >> 8);
}

#ifdef BYTE_ALGINED_REQUIRED
void short_copy_xch(void *dst, const void *src, int32_t nNumofShort, bool bSwitch)
{
    typedef uint8_t (*ARRAY2)[2];

    ARRAY2 pt = (ARRAY2)(dst);
    ARRAY2 ps = (ARRAY2)(src);

    if (bSwitch) {
        for (int32_t i = 0; i < nNumofShort; i++, pt++, ps++) {
            **pt = *(*ps + 1);
            *(*pt + 1) = **ps;
        }
    } else {
        for (int32_t i = 0; i < nNumofShort; i++, pt++, ps++) {
            **pt = **ps;
            *(*pt + 1) = *(*ps + 1);
        }
    }
}
#else
void short_copy_xch(void *dst, const void *src, int32_t nNumofShort, bool bSwitch)
{
    uint16_t *pt = (uint16_t *)dst;
    uint16_t *ps = (uint16_t *)src;

    for (int32_t i = 0; i < nNumofShort; i++, pt++, ps++) {
        *pt = bSwitch ? short_xch_hl(*ps) : *ps;
    }
}
#endif

#ifdef CALC_CRC_WITH_TABLE
static const uint16_t hwCRCTable[] = {
    0X0000, 0XC0C1, 0XC181, 0X0140, 0XC301, 0X03C0, 0X0280, 0XC241,
    0XC601, 0X06C0, 0X0780, 0XC741, 0X0500, 0XC5C1, 0XC481, 0X0440,
    0XCC01, 0X0CC0, 0X0D80, 0XCD41, 0X0F00, 0XCFC1, 0XCE81, 0X0E40,
    0X0A00, 0XCAC1, 0XCB81, 0X0B40, 0XC901, 0X09C0, 0X0880, 0XC841,
    0XD801, 0X18C0, 0X1980, 0XD941, 0X1B00, 0XDBC1, 0XDA81, 0X1A40,
    0X1E00, 0XDEC1, 0XDF81, 0X1F40, 0XDD01, 0X1DC0, 0X1C80, 0XDC41,
    0X1400, 0XD4C1, 0XD581, 0X1540, 0XD701, 0X17C0, 0X1680, 0XD641,
    0XD201, 0X12C0, 0X1380, 0XD341, 0X1100, 0XD1C1, 0XD081, 0X1040,
    0XF001, 0X30C0, 0X3180, 0XF141, 0X3300, 0XF3C1, 0XF281, 0X3240,
    0X3600, 0XF6C1, 0XF781, 0X3740, 0XF501, 0X35C0, 0X3480, 0XF441,
    0X3C00, 0XFCC1, 0XFD81, 0X3D40, 0XFF01, 0X3FC0, 0X3E80, 0XFE41,
    0XFA01, 0X3AC0, 0X3B80, 0XFB41, 0X3900, 0XF9C1, 0XF881, 0X3840,
    0X2800, 0XE8C1, 0XE981, 0X2940, 0XEB01, 0X2BC0, 0X2A80, 0XEA41,
    0XEE01, 0X2EC0, 0X2F80, 0XEF41, 0X2D00, 0XEDC1, 0XEC81, 0X2C40,
    0XE401, 0X24C0, 0X2580, 0XE541, 0X2700, 0XE7C1, 0XE681, 0X2640,
    0X2200, 0XE2C1, 0XE381, 0X2340, 0XE101, 0X21C0, 0X2080, 0XE041,
    0XA001, 0X60C0, 0X6180, 0XA141, 0X6300, 0XA3C1, 0XA281, 0X6240,
    0X6600, 0XA6C1, 0XA781, 0X6740, 0XA501, 0X65C0, 0X6480, 0XA441,
    0X6C00, 0XACC1, 0XAD81, 0X6D40, 0XAF01, 0X6FC0, 0X6E80, 0XAE41,
    0XAA01, 0X6AC0, 0X6B80, 0XAB41, 0X6900, 0XA9C1, 0XA881, 0X6840,
    0X7800, 0XB8C1, 0XB981, 0X7940, 0XBB01, 0X7BC0, 0X7A80, 0XBA41,
    0XBE01, 0X7EC0, 0X7F80, 0XBF41, 0X7D00, 0XBDC1, 0XBC81, 0X7C40,
    0XB401, 0X74C0, 0X7580, 0XB541, 0X7700, 0XB7C1, 0XB681, 0X7640,
    0X7200, 0XB2C1, 0XB381, 0X7340, 0XB101, 0X71C0, 0X7080, 0XB041,
    0X5000, 0X90C1, 0X9181, 0X5140, 0X9301, 0X53C0, 0X5280, 0X9241,
    0X9601, 0X56C0, 0X5780, 0X9741, 0X5500, 0X95C1, 0X9481, 0X5440,
    0X9C01, 0X5CC0, 0X5D80, 0X9D41, 0X5F00, 0X9FC1, 0X9E81, 0X5E40,
    0X5A00, 0X9AC1, 0X9B81, 0X5B40, 0X9901, 0X59C0, 0X5880, 0X9841,
    0X8801, 0X48C0, 0X4980, 0X8941, 0X4B00, 0X8BC1, 0X8A81, 0X4A40,
    0X4E00, 0X8EC1, 0X8F81, 0X4F40, 0X8D01, 0X4DC0, 0X4C80, 0X8C41,
    0X4400, 0X84C1, 0X8581, 0X4540, 0X8701, 0X47C0, 0X4680, 0X8641,
    0X8201, 0X42C0, 0X4380, 0X8341, 0X4100, 0X81C1, 0X8081, 0X4040
};
uint16_t crc16_with_table (uint16_t hwInitValue, const uint8_t * pchBuf, uint16_t hwLength)
{
    uint8_t chTemp;
    uint16_t hwCRCWord = hwInitValue;

    while (hwLength--) {
        chTemp = *pchBuf++ ^ hwCRCWord;
        hwCRCWord >>= 8;
        hwCRCWord  ^= hwCRCTable[chTemp];
    }
    return hwCRCWord;
}

#else
uint16_t crc16(uint16_t hwInitValue, const uint8_t *pchBuf, uint16_t hwLength)
{
    uint16_t hwCRC = hwInitValue;
    uint8_t i;

    while ((hwLength--) > 0) {
        hwCRC ^= *pchBuf++;
        for (i = 0; i < 8; i++) {
            hwCRC = (hwCRC & 0x0001) ? (hwCRC >> 1) ^ 0xA001 : hwCRC >> 1;
        }
    }
    return hwCRC;
}
#endif

bool valid_modbus_crc(const uint8_t *pchBuf, uint16_t hwLength)
{
    uint16_t hwCRC = 0;

    if (3 <= hwLength) {
        hwCRC = char_hl_short(pchBuf[hwLength - 1], pchBuf[hwLength - 2]);
        return hwCRC == MODBUS_CRC16(pchBuf, hwLength - 2);
    }
    return false;
}

/*************************** End of file ****************************/
